Dual Approach of Nanoemulsion and Natural Permeation Enhancer Endorse Skin Targeting of Acyclovir
Nikhil Shri Sahajpal,
Subheet Kumar Jain.
Background: In this study, nanoemulsion based gel formulation of acyclovir was prepared
in order to increase its topical effectiveness and target the disease site, which is the foremost limitation
associated with the topical marketed formulations of acyclovir.
Methods: In this study, nanoemulsion based gel formulation of acyclovir was prepared in order to
increase its topical effectiveness and target the disease site, which is the foremost limitation associated
with the topical marketed formulations of acyclovir. A w/o nanoemulsion in the strength of
5%w/w was prepared using probe sonication method and was characterized extensively in vitro, ex
vivo and in vivo to determine the quantity of drug that reached into skin to effectively treat the disease.
Results: Skin deposition across the rat skin was found to be 6.6 fold higher with developed nanoemulsion
based gel formulation in comparison to the marketed cream. The results of enhanced skin
permeation and deposition were deep-rooted by carrying out different mechanistic studies like FTIR
and CLSM of skin treated with prepared formulation. The rheological characterization study depicted
the shear thinning property and better structural recovery of nanoemulsion based gel (99.17±1.1%) as
compared to marketed cream (95.03±0.8%). Further in-vivo localization index, which was found to
be 60.33±0.9% and 19.21±0.6% for prepared gel and marketed cream, respectively, assured high
skin deposition and adequate penetration of the prepared gel to the different layers of skin with no
significant absorption into the systemic circulation.
Conclusion: Higher drug solubility, lower particle size, higher surface area and enhanced skin permeation
and deposition associated with prepared formulation seems to be responsible for its elevated
skin penetration which makes developed w/o nanoemulsion based gel as effective carrier for increasing
the local bioavailability of acyclovir.
Keywords: Acyclovir, localization index, local bioavailability, nanoemulsion based gel, rheological characterization, skin
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